Method of winning copper, nickel, and other metals

ABSTRACT

The invention is a process for winning nickel by treating an aqueous ammonium salt solution of nickel salts with a carbon monoxide-containing gas under reducing conditions to produce nickel carbonyl and subsequently recovering nickel therefrom. Optionally, the production of nickel carbonyl can be catalyzed, for example, by cyanide. Also, an essentially water-immiscible solvent for nickel carbonyl can optionally be employed. The aqueous ammoniacal solution is typically an aqueous ammoniacal ammonium chloride, carbonate, sulfate, hydroxide, or mixture thereof. The valuable metals associated with nickel, e.g., copper, cobalt, iron, and precious metals, are also separated and recovered by this process. The general nature of the process allows a wide variety of primary and secondary sources of nickel to be utilized by combining this process with a number of known ore-treatment steps.

United States Patent [191 Coffield et al. v

[ Nov. 27, 1973 METHOD OF WINNING COPPER, NICKEL,

AND OTHER METALS [75] Inventors: Thomas H. Coffield, Orchard Lake;Kestutis A. Keblys, Southfield, both of Mich.

Related U.S. Application Data 1 Continuation-in-part of Ser. No.717,034, Mar. 28,

1968, abandoned, which is a continuation-inpart of Ser. No. 807,987,Mar. 17, 1969.

[52] U.S. Cl 75/119, 75/103, 75/108,

75/117, 423/150, 423/143, 423/141 [51] Int. Cl C22b 3/00 [58] Field ofSearch 23/203 C; 75/119,

615,822 3/1961 Canada 23/203C 706,316 3/1965 Canada 23/203 C' 323,332l/l930 Great Britain 23/203 C OTHER PUBLICATIONS Blanchard, ChemicalReviews, Vol. 21, 1937, pp. 3, 10-12.

Primary Examiner-Herbert T. Carter I Attorney-Donald L. Johnson [5 7]ABSTRACT The invention is a process for winning nickel by treating anaqueous ammonium salt solution of nickel salts with a carbonmonoxide-containing gas under reducing conditions to produce nickelcarbonyl and subsequently recovering nickel therefrom. Optionally, theproduction of nickel carbonyl can be catalyzed, for example, by cyanide.Also, an essentially waterimmiscible solvent for nickel carbonyl canoptionally be employed. The aqueous ammoniacal solution is typically anaqueous ammoniacal ammonium chloride, carbonate, sulfate, hydroxide, ormixture thereof. The valuable metals associated with nickel, e.g.,copper, cobalt, iron, and precious metals, are also separated andrecovered by this process. The general nature, of the process allows awide variety of primary and secondary sources of nickel to be utilizedby combining this process with a number of known ore-treatment steps.

24 Claims, 9 Drawing Figures AQUEOUS AMMINE SOLN. OF METAL IONS Ni-(co)1'o RECOVERY co CONTG GAS-i REDUCTIVE CO COMPDS IN CATALYST --bCARBONYLATION SOLN o RECOVERY MAKE-UP a RECYCLE STREAMS- METAL aRESIDUEJF ANY FIGURE I INVENTORS T. H. COFFIELD K.KELBLYSPAIIEIIIEIIIIIII21 I975 3.775.099

SHEET 2 BF 9 A VENT GAs Pi, CRUSHINGBI I DRYING REDUCING GRINDING ORE NH:23 COKE,OIL,OR

3 2 T v 02 H2O REDucING GAs AMMONIA I OxIDATIvE COOLING sTRIPPING LEACH(NoN-OxIDIzING) REsIDuE SEPARATION Nio OF SOLID SINTER PRODUCT Ni CO3 BVENT GAS MU ORE ORE REDucING COOLING- PREPARATION COKE OR OII.,REDDOINGGAs NI REDucTIvE OxIDATIvE 2: RECOVERY CARBONYLATION LEACH H S 1 AIR ORRESIDUE' I 2 Co RECOVERY FIGURE 2 INVENTORS T. H.COFFIELD K.KEBLYSPATENIEDnnvzv ms SHEET 30F 9 A I COKE LATERITE CRUSH a KILN DRY SMELTINGoRE SCREEN a PRE-HEAT REHEAT 29 NI Co CAST O2 BLOW DESULFURIZEFERRONICKEL WITH 2 3 B COKE LATERITE CRUSH a KILN DRY ORE SCREEN.8|PREHEAT SMELT'NG GRANULATE Ni Ni REDUCTIVE OXIDATIVE RECOVERYCARBONYLATION LEACH NH co HO RESIDUE 212 AIR OR 0 Co.- Co

RECOVERY FIGURE 3 INVENTORS I. H.COFFIELD K.KEBLYS PAIENIEDNUVZ! I9753.775.099 SHEET I SF 9 A COKE COKE,GYPSUM,

l l LIMESTONE LATERITE CRUSH a SINTER SMELTING p ORE SCREEN BLASTFURNACE IRON-NICKEL MATTE NICKEL- AIR H RoAsT cRus a CONVERTER FLUID BEDGRIND SULHDE 5mg MATTE N02 s0 CAST ANODES TO CALCINE ELECTRO WINNINGCHARCOAL r L OXIDIZING NiO BRIQuETTE I ROAST a DRY REDUCE NICKELYRONDQELLES COKE coI E,sYPsuM,

l LIMESTONE LATERITE CRUSH a SINTER SMELTING ORE scREEN NH3,CO2 H2O AIROR 0 I AIR OX'DATIVE 1 GRANULATE coNvERTER LEACH NICKEL- z SULFIDE Nc|S0 MATTE REDUCTIVE Ni ME A CARBONYLATION REcovERY T L 00 METAL RECOVERYINVENTORS F|GURE 4 T. H. COFFIELD K. KEBLYS PATENTEDiinv 27 I975 3. 775O9 9 SHEET 5 OF 9 NH3 AIRYOR A co o SULFIDE CRUSHBi OXIDATIVE p GRINDBENEFICDATE LEACH ORE CONCENTRATE RESIDUE COPPER J 10% Ni O CONCENTRATE2 Cu H280 AlRl 30.7%Cu,O.5%Ni H S 4 J OXYDROLYSIS c c PPER COPPER STEAM425 OF SOLN STI IPPING BOIL i 600 PSIG Cu s To SMELTER NICKEL A H Ni Niamou- H Riz o fififoN oiv BR'QUETTE 2 POWDER POWDER ETTES SLURRY B 7 H2OAIR,NH3, COZIHZQ SULFIDE CRUSHB: OXIDATIVE GRIND BENEFICIATE LEACHNSIDUE METAL Ni REDUCTIVE RECOVERY CARBONYLATION- Cu 8 Co TO RECOVERYFIGURE 5 INVENTORS 'r. H.COFF|ELD K.KEBLYS PATENTEDIIIIV 27 I9753.775.099 SHEET 8 UF 9 SULFIDE CRUSH a NICKEL FLASH r BENEFICIATE OREGR'ND CONCENTRATE SMEVLTER COPPER J 35 Ni CONCENTRATE 0.5 A Cu 2% Cu 25/0 CU,I.2 /o 63 /0 NI 0 8 28% Cu Cu RESIDUE 7/ 3 LEACH CRUSH a CONVERTERTO SMELTER TWO'STAGE GRIND MATTE L H2 so v II II BLACK NICKEL COBALTELECTRO NICKEL M. M)

HYDROX'DE PRECIPITATION WINNING CATHQDES CO(0HI3 SULFIDE CRUSHBENEFICIATE FLASH ORE GRIND SMELTER lNH AIR OR 2 2 I I, Co a CuREDUCTIVE OXIDATIVE CONVERT'ER To RECOVERY CARBONYLATION LEACH NICKELRECOVERY NICKEL METAL FIGURE 6 INVENTORS T. H. COFF'IELD K. KEBLYSPATENTED NOV 2 7 I973 3.775.099 SHEET 7 BF 9 A CRUSH a N'CKEL TOP BLOWNp BENEFICIATE SULFIDE GRIND CQNCENTRATE CONVERTER R 0 E COPPERCONCENTRATE 27% Cu Fe(CO) NWCODI CARBONYL PREssuRE DRASTIC To FERROSEPARATION CARBONYLATION QUENCH NICKEL SOLID Ni CO3 RESIDUES T NICKELCAR- PRESSURE Ni,Co, C0 BONYL LEACH F SOLN PURIFICATION e COMPOSTIONPOWDER Cu g Fe TO WASTE SOLN.

Ni METAL SULFUR F REMOVAL UR souo PRECIOUS cu ELIECTIRO LEACH SMELTING WRESIDUES METALS l SLAG B SULFIDE CRUSH & Top BLOWN GRIND BENEF'C'ATECONVERTER NH3 AIR OR [00 0 REDUCTIVE OXIDATIVE DRASTIC To RECOVERYCARBONYLATION LEACH QUENCH RESIDUE TO PRECIOUS METALS RECOVERY NICKEL-NICKEL METAL RECOVERY INVENTORS 7 T. H.COFFIELD K.KEBLYS PAIENTEBnuv 27ms 3.775.099 SHIFT 8 CF 9 A Fe CONCENTRATE 60% Fe SULFIDE Ni CRUSHBENEFICIATE ROAST ORE GR'ND CONCENTRATE Cu CONCENTRATE SLOW VE R COOLCON RT SMELTE CRUSH BENEFICIATE ROAST GR'ND CONCENTRATE PRODUCT Co(OH)Cu CONCENTRATE NICKEL ELECTRO- CAST TO SMELTER METAL WINNING ANODES COKEl RESIDUE TO PRECIOUS Ni o METAL RECOVERY Ni(co) MONO REDUCE To DECOMPOCARBONYLATION SITION B SULFIDE c H a a, 223 BENEFICIATE ORE NH3 AIR 0RC0 2 OX'DATIVE CONVERTER SMELTER LEACH Cu 8 C0 REDUCTIVE NICKEL a N|cKE|METALI CARBONYLATIO TO RECOVERY N RECOVERY FIGURE 8 1 NVENTORS T. H.CQFFIELD K. KEBLEYS PATENTEDHUVZ? I975 3,775,099 -151 9 BF 9 AIR NH3 ACO2 H2O SCRAP Cu 8 Co 22w mszazimiw METAL TO RECOVERY RESIDUE NICKELMETAL 4 NICKEL RECOVERY FIGURE 9 BACKGROUND OF THE INVENTION Winningmetals has been a human activity since time immemorial. Civilization hasgrown with this art; and it is safe to say that the production of metalsis the genesis and sustenance of many aspects of modern technology. Atthe present time, mankind utilizes metals at a large and rapidlyincreasing rate. For this reason, improvements in techniques forobtaining metals have immediate interest.

The above facts are adequately illustrated by the history of copper.Mankind emerged from the Stone Age upon discovery of copper in itsnative form. The dawn of the Bronze Age was circa 8,000 BC. when it wasdiscovered that this copper-tin alloy could be readily shaped intoimplements and weapons. Copper deposits on Cyprus were worked as earlyas 3,000 B.C. by the Egyptians and these deposits became the chiefsource of the metal for the Roman Empire. In 1556, Agricola recorded thehistory of copper. In 1963, world refined copper output exceeded3,800,000 short tons.

Nickel was isolated by Cronstedt in 1751. By 1804, the properties of thepure metal were known with reasonable accuracy.

Referring to the section on copper in Kirk-Othmer Encyclopedia ofChemical Technology, second edition, volumn 6, page 131, and The Winningf Nickel, by Boldt, Jr., et al, D. Van Nostrand Co., New York, N. Y.(1967), the production of copper and nickel from ores are tedious,complex processes. Clearly, commerce could not bear the cost of suchmulti-step processes if these metals were not so important. A detaileddiscussion of all ramifications of art-known methods for the productionof copper and nickel would be out of place here. It is sufficient torelate the following facts.

Copper and nickel are both present in some ores worked today. Since 1899nickel has been refined by the Mond process which comprises reactingnickel with carbon monoxide to form nickel carbonyl and subsequentdecomposition of this product to carbon monoxide and nickel. In thesection on nickel in Kirk-Othmer (supra), second edition, volume 13,page 735, (739) there is described a hydrometallurgical refining processfor nickel (practiced by Sherritt Gordon Mines Limited of Toronto,Canada). In this process, concentrates of pentlandite, (Ni, Fe) S aredissolved in an aerated ammoniacal solution. The nickel, copper andcobalt sulfides dissolve as ammines, with iron remaining in the residueas hydrated ferric oxide. Subsequently, copper is precipitated, and theremaining nickel solution is oxidized to destroy sulfamate. Theresultant solution is treated with hydrogen at 35 atmospheres and 190C.to yield 99.9 percent nickel which is sintered into briquettes.

The Sherritt Gordon process is described in more detail in Boldt, Jr.(supra), page 299 ff. As described therein, the copper is removed fromthe ammoniacal solution by boiling off ammonia to precipitate cupricsulfide. The last traces of copper are removed by adding H 5. This mustbe done before nickel is precipitated with hydrogen, to avoidcontamination of the nickel with copper.

In general, nickel and associated metals are recov-' ered and separatedby pyrometallurgical, hydrometallurgical, or electrolytic refiningtechniques. For sulfide ores, the general operations of roasting,smelting, and converting produce a nickel matte product which issuitable for refining to pure metal electrolytically. In contrast tosulfide ore processing, the oxide ores may be more economicallyprocessed by hydrometallurgical or carbonyl processes to produce veryhigh purity nickel. However, this is not true in all cases since onecommercial operation utilizes pyrometallurgical techniques to prepareferronickel from a laterite ore. A roasting operation decreases thesulfur content of a sulfide ore concentrate by about one-half. Previousprocesses have used multiple hearth furnaces, sintering machines, orfluidized bed reactors. When followed by smelting operations using shaftfurnaces, reverberatory furnaces or electric arc furnaces to slag offsiliceous and other oxide compounds, a typical nickel sulfide mattecontaining about 15 percent nickel-copper, 50 percent iron, and 25percent sulfur is produced. This nickel-sulfide matte is then charged toa converter and air is blown through the charge to oxidize iron sulfideselectively. Usually, horizontal converters are used. Recently a processusing a top-blown rotary converter in which an oxygen lance is blownonto the surface of the molten charge has been placed in successfulcommercial operation. The nickel sulfide matte essentially free of ironproduced in the converting operation, typically contains about 48percent nickel, 27 percent copper, 22 percent sulfur, and less than 1percent iron. This matte is sulfur deficient and, therefore, contains ametallic phase which must be processed to separate the nickel sulfideand copper sulfide. In one process, a slow coolingstep is used wherebythe sulfur deficient matte cast from the converter is cooled slowly overa period of several days. The nickel sulfide, copper sulfide, andcopper-nickel metallics separate, allowing regular ore dressingoperations to be used to separate the solidified matte into itscomponents. Thus, the nickel-copper alloy is removed magnetically andthe nickel and coppersulfides are then separated by flotation. Thenickel sulfide can then be either sintered to provide percent nickel fordirect use by steel producers, or roasted to the oxide, smelted and castinto anodes for electrorefining. Alternatively, the nickel sulfide mattecan be cast directly into anodes for electro-refining.

In electrolytic refining, metallic nickel of high purity is produced. Amajor portion of the worlds nickel production includes this process as alast step in winning nickel. In addition, the recovery of preciousmetals and other elements such as cobalt is practiced. A dividedelectrolyticcell with a porousdiaphragm separating the anode and cathodeis used in the electrolytic process. The diaphragm prevents impureanolyte from directly contacting the nickel cathode starting sheet. Theimpure anolyte obtained by solution of the anode is pumped away from thecell to another area where impurities are removed. The nickel cathodescontaining 99.9 percent nickel are removed after about l0 days operationof the cell.

In addition to the Sherritt Gordon process described above, otherhydrometallurgical refining processes are commercially employed to winnickel by gaseous reduction of nickel salt solutions derived from bothsultide and oxide ores. Preparatory ore-dressing treat ments provide auniform feed for the reduction and leaching process. Leaching proceduresvary depending on the particular ore treated. However, the nickelcarbonates produced from the aqueous solution are calcined to marketablenickel oxide, or further sintered to upgrade the nickel metal content toabout 88 percent. A process to recover nickel and cobalt from alimonitic-type laterite ore from Cuba treated the ore with sulfuric acidat elevated temperature and pressure to dissolve nickel and cobaltpreferentially. The iron remained essentially undissolved. The liquidseparated from the residue contained 95 percent of the nickel found inthe ore. After further purification of the aqueous phase, the nickelsulfate is reacted with hydrogen at high pressure and at about 190C. torecover most of the nickel as a 99.8 percent pure product.

Nickel is also produced in the form of ferronickel and nickel rondelles.Ferronickel is produced by a pyrometallurgical process of melting,reduction, and refining. One commercial process in New Caledonia reducesthe ore with coke in electric furnaces. Another commercial process inOregon involves mixing molten ore with ferrosilicon and crudeferronickel. By pouring the molten materials back and forth in specialladles, the molten ore is reduced and the resulting ferronickel productcontains about 48 percent nickel. This crude product is further refinedto lower the impurity level. Nickel rondelles are produced by reactingthe ore with coke and gypsum in blast furnaces, blowing the nickel-ironmatte and a siliceous flux with air and converting to produce alow-sulfur nickel matte, roasting to the oxide, grinding, compacting,and reducing to the metal with charcoal. The resulting nickel rondellescontain 99 percent nickel.

Data on the reduction of copper (II) salts with carbon monoxide has beenpublished; Byerley et al., Met. Soc. Conf., 24, 183 (1963); Chem. Abs.64, [3441 h (1966). Conversion of aqueous nickel to nickel carbonyl hasbeen disclosed in Chem. Abs. 53, 12606 h (1959).

SUMMARY OF THE INVENTION Discoveries on which this invention is basedare as follows:

1. The reduction of copper (II) salts to copper metal with carbonmonoxide is promoted by the presence of nickel carbonyl,manganesecarbonyl, or cobalt carbonyl.

2. With ammoniacal solutions of copper and nickel salts, it is notnecessary to separate copper before winning the nickel.

3. Cupric salts can be reduced to copper metal simultaneously and in thesame reaction zone wherein nickel carbonyl is produced from nickel (II)salts, via use of carbon monoxide or synthesis gas treatment.

4. The reduction of nickel (II) salts to nickel carbonyl with carbonmonoxide is promoted in the presence of a ligandselected from cyanide,sulfide, cysteinc, and tartrate.

5. Practically complete conversion and separation of nickel, copper, andcobalt is possible by treating ammonium salt solutions of those metalsprepared from an ore, an ore concentrate such as a beneficiated raw oreconcentrate, a nickel-iron or a nickelsulfur matte, or a ferronickelproduct, with carbon monoxide or synthesis gas under conditions wherebythe nickel and cobalt values are reduced to form metal carbonylcompounds, and the copper is reduced to metallic copper.

Based on these discoveries, this invention is a process for winningnickel by treating a nickel-containing solution of various metal ionswith a carbon monoxidecontaining gas and forming a nickel carbonylcompound which can be easily separated from the solution and from othermetal compounds or metals. Moreover, valuable metals associated withnickel, e,g., cobalt and copper, may be simultaneously converted tocarbonyl compounds or reduced to the metallic state and, thereafter, beeasily separated and recovered.

In part, this invention also resides in new improved processes forseparation of nickel, cobalt, copper, and iron from ores (or othermaterials) containing these metals. Such processes are outlined below asfollows.

A source of nickel, copper, cobalt, and iron, such as a sulfide-typenickel ore concentrate, is treated with aqueous ammonia and aerated. Theresulting aqueous ammonia solution after removal of the precipitatediron contains nickel, copper and cobalt values as ammine sulfates. Thissolution is put in a reaction zone having a surface suitable forsubsequent copper deposition or alternatively, the solution can beseeded with finely divided copper. In either event, the ammoniacalsolution is thereafter treated with carbon monoxide or synthesis gasunder pressure. As reduction proceeds, nickel ion is reacted to nickelcarbonyl. This can be removed and decomposed thermally to nickel powder.During the reduction step, copper ion is reduced to the metal anddeposited. The copper is removed from the reaction zone. During thereduction step, cobalt ion is reduced to the cobalt tetracarbonyl anionwhich remains in the solution. As such, it can be separated from nickeland copper. The cobalt can be recovered by injecting anoxygen-containing gas into the solution whereby cobalt is oxidized tohydrated cobalt oxide. It is then filtered from the solution and heatedto remove the waters of hydration. After cobalt removal, the solutioncontains ammonium sulfate, which is isolated as a by-product.

Another process for winning nickel is to prepare an ammonium saltsolution of a laterite ore by crushing and grinding the ore to a fineuniform feed of approximately constant composition, roasting the ore ina reducing atmosphere typically with producer gas, cooling the reducedore under non-oxidizing conditions, leaching the reduced ore with anaqueous ammonium salt to solubilize nickel and cobalt. The ammonium saltsolution is treated with carbon monoxide under conditions to form nickeland cobalt carbonyl compounds, each of which may be separated andrecovered.

Still another process contemplated by this invention is the oxidativeleach and carbon monoxide or synthesis gas treatment of a ferronickelproduct produced from either an oxide or sulfide ore. Recovery of nickeland cobalt proceeds as before from the carbonyl compounds produced.

A still further process for winning nickel is the oxidative leach andreductive carbonylation of a furnace or converter matte produced byconventional procedures from a convenient source of either sulfide orlaterite ores. After the matte is produced, it is treated by anoxidative leach with an ammonium salt solution to dissolve the desiredmetals. Treatment of the resultant solution with a carbonmonoxide-containing gas reacts nickel and cobalt, and if present,copper, to the abovestated forms which can be separated and recoveredfrom the solution.

In addition, nickel may be recovered from scrap metal containing arecoverable quantity of nickel by comminuting the scrap, dissolving thenickel values selectively, using an oxidative leach with an ammoniumsalt solution and treating said solution with a carbonmonoxide-containing gas. The nickel is reduced to a carbonyl compoundand separated and recovered from the solution. Other metal values suchas copper and cobalt associated with the scrap metal may also berecovered according to this process.

Nickel may also be recovered from manganese nodules found on the deepsea floor. The nodules are comminuted, subjected to a reducing roast,cooled under non-oxidizing conditions, and leached with an aqueousammonium salt to solubilize the nickel values, as well as copper andcobalt. The solution is treated with a carbon monoxide-containing gasunder conditions to form metal carbonyl compounds or the metal itself inthe case of copper. The valuable metals are then recovered as previouslydescribed.

In each case, briefly described above, a promoter may be employed toaccelerate the formation of the carbonyl compounds.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of theproduction of nickel carbonyl from a solution containing nickel ions byreacting said solution with a carbon monoxide-containing gas in thepresence of a catalyst.

FIG. 2 shows in Part A a schematic representation of the Nicaro processfor producing a nickel oxide product from ore by a process of. drying,reducing and cooling under non-oxidizing conditions, leaching thereduced ore, stripping ammonia from the leach solution, separatingnickel carbonate from the solution, and sintering to produce nickeloxide. Part B of FIG. 2 represents the combination of a Nicaro processwith reductive carbonylation wherein the schematic representation showsa reductive carbonylation step after the oxidative leach with subsequentmetal recovery.

FIG. 3 shows in Part A the preparation of ferronickel from a nickel oreby smelting the ore,'desulfurizing the molten ore with sodium carbonate,blowing the desulfurized melt with oxygen to produce a ferronickelproduct. Part B shows the combination of the smelting operation with anoxidative leach and reductive carbonylation and recovery of nickel metalinstead of the ferronickel product.

FIG. 4 is a schematic representation in Part A of the production ofnickel rondelles from a nickel sulfide matte. In this process after alaterite ore is sintered and smelted in a blast furnace, the blastfurnace matte is converted to a nickel sulfide matte by blowing withair. The converter matte is then roasted in a two-stage process tonickel oxide briquets which are then reduced to nickel rondelles. Part Bshows a schematic representation of a process combining the nickelsulfide matte process with an oxidative leach solution and reductivecarbonylation to produce nickel metal.

FIG. 5 is a schematic representation in Part A of the Sherritt Gordonprocess for obtaining nickel briquets from a sulfide ore using ahydrometallurgical process. Part A shows the beneficiation of a sulfideore and oxi dative leach of the nickel concentrate produced withsubsequent copper removal and oxydrolysis of the nickel to nickelsulfate. Reduction of this solution with hydrogen produces a nickelpowder which is dried and briquetted. Part B of FIG. 5 represents thecombination of the Sherritt Gordon process with reductive carbonylationwherein reductive carbonylation is carried out on the leach solutionandnickel metal is recovered.

FIG. 6 is a schematic representation in Part A of the production ofnickel by a process of flash smelting a nickel concentrate, convertingthe molten metals to a nickel sulfide matte, leaching the matte in atwo-stage process to separate nickel from copper, reacting the leachsolution with black nickel hydroxide to precipitate cobalt, andelectrolysis of the nickel-containing solution to produce highly purenickel cathode sheets. Part B of FIG. 6 schematically represents thecombination with reductive carbonylation of the above process wherein anoxidative leach step is carried out after either the flash smeltingoperation or the converting operation. The leach solution iscarbonylated and nickel metal recovered.

FIG. 7 represents in Part A a schematic process for production of nickelfrom a sulfide ore by a process of converting a nickel concentrate in atop-blown rotary converter to produce a molten nickel sulfide 'meltwhich is drastically quenched in water. The granulated melt is subjectedto carbonylation under high pressure, and the carbonyls are separated toproduce nickel metal and ferronickel. The solid residues from pressurecarbonylation are leached and purified to produce other metals. Part Bof FIG. 7 shows the combination of reductive carbonylation with thetop-blown rotary converter operation described above. After converting anickel concentrate to a low-sulfur molten nickel matte and quenching,the granulated nickel matte is ox- I idatively leached and subjected toreductive carbonylation. Nickel metal is recovered.

FIG. 8 is a schematic representation in Part A of a process for winningnickel by roasting a nickel concentrate, smelting the roastedconcentrate, and converting the matte produced to a nickel sulfidematte. The nickel sulfide matte is allowed to cool slowly and separatesinto its various metallic phases. The solid matte is again beneficiated,roasted, and smelted, and the high nickel matte is cast into anodes forelectro-winning of nickel metal. In Part B, the combination of oxidativeleach and the reductive carbonylation is added after the nickel isroasted, smelted and converted to produce a nickel matte. The matte isleached and carbonylated to produce nickel metal.

FIG. 9 is a schematic representation of a process for recovery of nickelmetal from scrap metal. The scrap is comminuted and then oxidativelyleached, subjected to reductive carbonylation, and nickel metal isrecovered.

DESCRIPTION OF PREFERRED EMBODIMENTS The invention is a process forrecovery and separation of nickel and metal values associated therewithderived from a sulfide or laterite source of nickel ore. The processcomprises establishing a solution or slurry containing nickel and themetal values associated therewith from which iron has been removed andcontacting said solution or slurry with a carbon monoxidecontaining gasto form carbonyl compounds of the metal values. The nature andproperties of the carbonyl compounds allow easy and complete separationof the metal carbonyl compounds from the solution or slurry.

As a convenient source of metals for the process of this invention,materials rich in nickel such as sulfide or laterite ores and theprocessed materials derived therefrom such as concentrates, mattes, andleach solutions, and scrap metal, and ocean nodules may be treated. Thetreatment of the source of nickel and metals associated therewith islargely a matter of choice, depending upon the type of ore, itssituation in the natural state, or the economics of obtaining aconvenient source of metal values to be treated by the process of thisinvention.

Establishment of a solution or slurry from the source of ores describedabove can be by solubilization, selective leaching, or physicalseparation of metallic constituents, as for example by flotation. Inshort, any art recognized method of obtaining a solution or slurry ofnickel and associated metals may be used to prepare a solution or slurrysuitable for subsequent carbonylation. The concentration of metals inthe solution or slurry may vary widely. Indeed, any concentrationconveniently obtained may be used to produce nickel and associatedmetals by the process of this invention. Diluted solutions, saturatedsolutions, or super-saturated solutions, for example slurries, may beused in the separation and recovery of nickel and associated metals inthis process.

Any means which the art has recognized as sufficient to dissolve nickeland its associated metals may be used to prepare a solution or slurry ofsaid nickel and associated metals. The only requirement is that thenickel be in a form that has at least some water-solubility or that itis rendered soluble by the action of a coordinating agent such asammonia. The anion associated with the nickel is not critical. Forexample, the nickel may be in the form of the water soluble nickel saltssuch as nickel acetate, nickel ammonium chloride, nickel ammoniumsulfate, nickel bromide, nickel chloride, nickel fluoride, nickeliodide, or nickel sulfate. The nickel may be in a normally insolubleform which is rendered at least partially soluble by an agent such asammonia. These nickel compounds would include nickel carbonate, basicnickel carbonate, nickel oxide, nickel phosphate, nickel hydroxide, andthe like.

The aqueous reaction media may be water or watercontaining an ammoniumsalt. The function of the ammonium salt is to at least partiallysolubilize the nickel compound. Useful ammonium salts include ammoniumchloride, ammonium carbonate, ammonium sulfate, ammonium phosphate,ammonium bromide, ammonium iodide, ammonium phosphite, ammonium sulfite,ammonium cyanide, ammonium fluoride, ammonium sulfide, and the like,including mixtures thereof. The reaction media may also be aqueousammonium hydroxide.

The concentration of the ammonium salt solution is not critical. Asstated above, it is not even required when the nickel compound has somewater solubility. When required, a preferred concentration range is fromabout 0.1 wt. up to a saturated ammonium salt solution. In general, goodresults are obtained using a 2-20 wt.% aqueous ammonium salt solution. Amost preferred range is from about 3-10 wt. ammonium salt.

Most preferred aqueous reaction media are ammoniacal ammonium saltsolutions. These are solutions of ammonium salts such as the abovecontaining dissolved ammonia. The amount of excess ammonia can range upto complete saturation of the aqueous media. A preferred amount ofammonia is from about l-40 wt. NH A more preferred range is from 2-20wt.% NH;,, and a most preferred NH concentration is from about 2-10wt.%.

The amount of ammonium salt in the aqueous reaction media should be atleast sufficient to provide on an equivalent basis an amount of anionsequal to the amount of metallic nickel, copper, or cobalt present.Preferably, the amount of anions provided by the ammonium salt should bein excess of the equivalents of metallic nickel, copper, or cobaltpresent. A useful range based on the equivalent of nickel, copper, andcobalt present is from stoichiometric to about equivalents of anion perequivalent of the above metals. It is apparent from the above, forexample, that a low sulfur matte will require more ammonium salt in theaqueous reaction media than a high sulfur matte because it will containmore metal inthe metallic state requiring more anions to be supplied bythe ammonium salt to dissolve or leach the matte into solution.

When the nickel is at least partially dissolved, the resultant solutionor slurry is treated with a carbon monoxide-containing gas. An amount ofthe carbon monoxide-containing gas at least sufficient to combine withnickel and its associated metals is introduced into the solution by awide variety of methods. The particular method of introduction is notcritical. The only requirement being that intimate contact of thesolution and carbon monoxide-containing gas is established. A preferredcarbon monoxide-containing gas is carbon monoxide. However, synthesisgas, a combination of hydrogen and carbon monoxide, may also be used. Apreferredmethod of treating the solution is to introduce the carbonmonoxide-containing gas under superatmospheric pressure. Pressures ofcarbon monoxide from 50 to about 3,000 psig. may be employed. Apreferred rane of carbon monoxide pressure is from 50 to about 1,800psig.

One skilled in the art will readily see that pressure is not an entirelyindependent variable but depends upon the system being treated. That is,the type of ore and the type of salt solution will affect the pressurerequired to carry out efficient carbonylation.

Temperatures at which the carbonylation process is can'ied out are thosewhich facilitate a desirable rate of reaction and also allow convenientprocessing equipment to be utilized. Temperatures depend on the type offeed and the aqueous reaction media used in the carbonylation process.Thus, the temperature is in many instances dependent upon the pressure,feed and rate of reaction desired. A general range of temperatures underwhich carbonylation can be carried out are from 50 to about 250C. Apreferred range of temperatures is from about 100 to about C.

It has been found that the reaction of the carbon monoxidecontainingammoniacal salt solution is accelerated in the presence of certainpromoters. The method by which such acceleration takes place is notfully understood. However, the rate of carbonylation is markedlyincreased by addition of certain promoters. It has been found that suchpromoters are ligands selected from alkoxide anions, organic acidanions, inorganic acid anions, and inorganic anions. A preferred groupof ligands found to be useful in promoting the carbonylation process arecysteine and tartrate, sulfide and cyanide. A preferred promoter ligandis cyanide ion. The manner of introducing the promoter into the reactionmedium is not critical and the only requirement is that the catalyticspecies be soluble in the reac tion medium. A preferred amount of thepromoter or catalyst ligand is a catalyst-to-nickel ratio of 0.0l1 moleof promoter per mole of nickel. A preferred range is from 0.010.5. Itshould be'understood that the particular catalyst concentration usefulin the process of this invention depends on the reaction system employedand the feed material being carbonylated.

The duration of the reaction is a function of the system beingcarbonylated and may vary depending on the pressure, temperature, thetype of feed, and the solubilizing agent and the use of a catalyst.Under the broad range of conditions employed, carbonylation reactiontimes of up to about ten hours have been noted. However, under preferredconditions, the reaction is essentially completed after about two hours.In fact, the major portion of the reaction is completed within the firstone-half hour when a catalyst is employed. Completion of the reaction isshown by a sharp decrease in I rate of pressure drop in the reactionvessel. It should be understood that the reaction time is not acompletely independent variable and can be varied according toreasonable requirements of the individual reaction system.

In a preferred process, the nickel and associated metals, after beingtaken into solution, are carbonylated in an ammonium salt solution. Amost preferred embodiment is the use of an aqueous ammoniacal ammoniumcarbonate solution wherein ammonia and carbon dioxide are added to anaqueous media which is used to leach the nickel and associated metalsfrom their source material. In general, the solutions use a ratio ofammonia-to-metal in the ammonium salt solution of from zero to 1 toabout 100 to 1 moles of ammonia per mole of metal. A preferred amountofammonia in such a system is from to 50 moles of ammonia per mole ofmetal in the solution. A most preferred range is from 0 to 10 moles ofammonia per mole of metal in solution.

The nickel carbonyl formed by the reaction of the carbonmonoxide-containing gas and the nickel may be separated from thereaction solution by taking it up in a water-immiscible, substantiallyinert solvent for nickel carbonyl or by sweeping out the reaction vesselwith additional carbon monoxide-containing gas. The exact nature of thesolvent is not critical so long as it is immiscible with water,dissolves nickel carbonyl, and is substantially inert under the reactionconditions. In a preferred embodiment, a solvent less dense than wateris used. Nickel carbonyl is soluble in many organic solvents such asparaffins, mixtures thereof, benzene, toluene, and carbon tetrachloride.Preferred solvents are paraffin fractions such as ligroin, gasoline,kerosene, and paraffinic materials such as cyclohexane, heptane, octane,nonane, and the like. Normal or branched chain paraffins can be used aswell as mixtures thereof. A most preferred solvent is a saturatedaliphatic hydrocarbon such as hexane, heptane, octane, nonane, decane,dodecane, their branched chain derivatives, mixtures of these, and thelike.

The amount of solvent which is used is not critical. It is onlynecessary to use the amount of solvent required to dissolve the desiredamount of nickel carbonyl. There is no real upper limit on the amount oforganic solvent, this being defined by such considerations as economics,size of the reaction vessel, ease of separation of nickel carbonyltherefrom, and the like. Generally from 0.1 to 2 volumes of organicsolvent are used per unit volume of aqueous reaction media. Preferablyfrom 0.1 to 0.5 volumes are employed.

As stated above, the nickel carbonyl may also be separated from thereaction media by passing a carbon monoxide-containing gas through thesolution, allowing the nickel carbonyl to vaporize into the carbonmonoxide-containing gas. When the reaction is completed, nickel carbonylis present both in the vapor phase above the reaction solution anddissolved in the solution itself. As the pressure is released, the vaporphase containing the carbon monoxide-containing gas and vaporized nickelcarbonyls is vented to a nickel carbonyl recovery zone, for example, athermal decomposition zone. Additional carbon monoxide-containing gas isintroduced through the solution and nickel carbonyl vaporizes into thegas and it is passed out of the reaction vessel into the recovery zone.Thus, substantially complete removal of nickel carbonyl is obtained. Thecarbon monoxide-containing gas used to sweep out the nickel carbonyl maybe the same as that employed to react with the nickel. As stated above,preferred carbon monoxide-containing gases are carbon monoxide andsynthesis gas. The amount of sweep gas is not critical and depends onthe reactor size, temperature, and pressure of the system. Generally,from about 1 to 1,000 volumes of the carbon monoxide-containing gas issufficient.

Referring again to the drawings, FIG. 1 is a schematic representation ofthe general process of this invention. The block labeled reductivecarbonylation represents a suitable reactor in which the process iscarried out. Any convenient reaction vessel may be utilized within thelimitation of sound engineering and economic principles. A feed ofaqueous ammine solution containing metal ions; e.g., nickel, copper,cobalt, and the like, is charged to the reactor. Catalyst (e.g., cyanideion) is added and the reactor is pressurized with a carbonmonoxide-containing gas. Any recycle stream containing recovered metalions from the solution or residue, if any, or additional ammine solutionrequired will be deposited in the reactor and can then be recovered. Ifother impurities in the solution are presenna residue may form and thecopper must be separated therefrom.

This general process can be varied as appreciated by one skilled in theart, without departing from the scope of the invention. For example, asdescribed above, a solvent for nickel carbonyl may also be added to thereaction mixture. lts purpose is to selectively solvate the nickelcarbonyl formedand provide a means for removing it from the system. Thereaction may also be run on a continuous basis with appropriatemodifications for maintaining the pressure, temperature and reactionrate. In such a case, the reaction solution withdrawn must be processedto remove unreacted metal ions and recycle them to the reactor ifrequired.

The process is further illustrated by the following examples. All partsare by weight unless otherwise stated.

EXAMPLE 1 A glass lined rocking autoclave was charged with 5.0 g. ofcopper sulfate pentahydrate, 5.25 g. of nickel sulfate hexahydrate, 21ml. of concentrated ammonia, 25 ml. of water, and ml. of heptane. Theautoclave was pressured with 640 psig. hydrogen and 1,200 psig. carbonmonoxide, then heated 2 hours at 150C.

The resultant mixture consisted of a colorless heptane phase, metalliccopper, and a light blue aqueous solution. The heptane phase wassiphoned off and combined with subsequent heptane extracts of aqueousphase. The nickel carbonyl and heptane solution was treated with excessbromine in carbon tetrachloride. The resulting mixture was filtered,washed with carbon tetrachloride and dried. This gave 2.55 g. of nickelbromide. This corresponds to a 58 percent yield of nickel carbonyl basedon starting nickel sulfate.

The copper metal was filtered, washed and dried in vacuo, yielding 0.90g. of copper metal. This corresponds to a 71 percent yield based onstarting copper sulfate.

This example illustrates that cupric salts present in an ammoniacalaqueous solution can form metallic copper in the presence of hydrogenand carbon monoxide even though nickel salts are present in the pregnantsolution. It also illustrates that nickel (II) and salts in aqueousammoniacal solution form nickel carbonyl in the presence of copperammines. There is another facet to the example, Specifically, the coppermetal and nickel carbonyl were separable in the absence of an overtcontamination of either product; even though hydrogen gas was present inthe reducing atmosphere. This example also illustrates that it ispossible to extract nickel carbonyl with an essentially water-immisciblesolution while reductions are taking place.

EXAMPLE 2 A pregnant aqueous solution contains in grams per liter:

nickel 45 cobalt 0.7

copper 7 ammonium sulfate 150 free ammonia 95 This solution is treatedwith 0.05 gram per liter of cop per powder (finely divided) and then fedinto a pressure vessel. The reaction vessel is charged with heptane sothat the ratio of volume of pregnant solution to heptane is 10 to 1. i

The pressure vessel is equipped with a stirrer which is activated. Then,the sealed vessel is charged with 800 psig. of synthesis gas at 175C.The vessel contents are maintained at this temperature for 2 hours.After that time, the stirrer is turned off and the vessel contentsallowed to cool to ambient temperature.

Thereafter, the aqueous layer is drawn off and the copper metal removedby filtration. The filtrate is sent downstream for recovery of cobaltvalues and ammonium sulfate by-products.

The heptane layer is drawn off and the nickel carbonyl separated bydistillation. in this example, ninetenths of the nickel carbonyl isdecomposed to form nickel metal powder. The remaining one-tenth isreacted with bromine to form nickel bromide.

This nickel bromide is used to form nickelocene according to US. Pat No.2,680,758. The nickelocene can be further reacted according toprocedures in US. Pat. No. 3,054,815, to form other ogano nickelcompounds. In addition, it is appreciated by a skilled practitioner thatnickel carbonyl, nickel bromide, or nickelocene can be directly orultimately used to form antiknock compounds such as those described inUS. Pat. Nos. 3,086,035, 3,086,036, 3,086,037, 3,086,034, 3,086,984,3,088,962, 3,088,963, 3,097,224, 3,097,225, etc.

The process of Example 2 can be used to treat solutions having in gramsper liter:

nickel 4O 5O cobalt 0.7 1

copper 5 10 ammonium sulfate 120 180 free ammonia Likewise, solutionshaving greater or lesser quantities of these substituents can be sotreated.

Likewise, the process of the preceding example can be used to treatconcentrates having nickel 10 percent, cobalt 0.5 percent, copper 2percent, iron 38 percent, sulfur 31 percent and rock 14 percent byleaching such a solid pentlandite flotation concentrate with aeratedammonia and then treating the concentrate with synthesis gas underconditions as set forth in the preceding example.

Similarly, the procedure of the above example can be employed using atemperature of from 100 to 250C., a H pressure of from zero to 1,200psig., a carbon monoxide pressure of from 200 to 1,200 psig., a time offrom 1 to 4 hours, an amount of organic solvent (per unit volume ofaqueous solution) of from 0.1 to 2.0, said solvent being selected fromligroin, n-octane, kerosene, n-nonane, and cyclohexane.

The procedure of the above examples can be extended to recovery of Ni,Cu, Co, Fe and precious metals. Thus, a sulfide concentrate containingthese metals is smelted in air in a smelting furnace. lron values can berecovered as known in the art and separated from a matte containing(some iron), nickel, copper, cobalt, and precious metals.

The matte is subjected to a pressure oxidation to yield soluble amminesulfates of nickel, cobalt, and copper.

Iron values and precious metals are in the residue. The precious metalsare recovered as known in the art. The ammine sulfates are treated as inthe previous examples to recover and separate copper, nickel, andcohalt.

The use of a catalyst for the formation of nickel carbonyl is apreferred embodiment of the invention and is illustrated by thefollowing examples.

EXAMPLES To a reaction vessel equipped with a stirrer was added 327millimoles ammonium hydroxide (13.6 molar solution), 54.5 millimolesNiSO enough water to make a total volume of 100 ml. and then 10 ml. ofheptane. The reaction vessel was closed and sealed, pressure lines wereconnected and the vessel flushed with nitrogen. After pressuring withnitrogen to 60 psig., the autoclave was heated to C. On reachingtemperature equilibrium, the reaction vessel was pres- 4 Mmoles productfound over mmoles of starting metal sulfate.

sured further to about 600 psig. with carbon monoxide. The reaction wascontinued for 3 hours. The total pressure drop in the reaction was 235psi. After rapid cooling, the autoclave was vented.

The organic layer was separated. The amount of nickel carbonyl wasdetermined by decomposition with bromine. The yield of nickel carbonylwas 30 percent. The aqueous phase contained unreacted nickel sulfatecorresponding to 51 percent of the amount charged.

The following table shows effect of the addition of cyanide ion in theform of potassium cyanide, KCN. The reaction procedure is substantiallythe same as in Example 3 above. The various Examples 4-9 illustrate theeffectiveness of the addition of a small amount of cyanide ion to thereaction mixture. Further, the catalysis by cyanide ion is not affectedto any substantial extent by the presence of other metal ions.

TABLE I [Cyanide-Catalyzed Reduction of Nickel, Cobalt, and Coppersulfates] Example No.

Reaction variables:

Initial molar ratios:

NiS04 9 110 110 110 101 110 C0804 12 12 CuSO4. 27 27 KC 1 1 1 1 1 1Total pressure drop, p.s.i 395 410 410 425 400 315 Reaction time,hrs. 1. 5 2. 2 2. 2 2. 5 3. 0 3. 0 Duration of gas uptake, hrs 0.75 18 1. 8 1 2.5 9 3. 0 1 3. 0 Results percent:

Recovered:

NiSO4 4. 8 1.9 1 9 2.4 8 8 30.8 C0804 3 .3 74.7 011804- 7. 6 47. 2Conversion 4 to Ni(CO)4 90 98 98 94; 92 72 Conversion 4 to Cu metal. 6353 1 54.5 moles of NiSO; used in each run. The metal sulfate-ammoniaratio was 1:6 in each run. Total volume of each run was 100 ml. ofaqueous phase and ml. of heptane. All runs were carried out at 150 C.and 600 p.s.i. initial carbon monoxide pressure. Examples 4-9 wererepressured three times back to 600 psi.

1 Gas was still being taken up very slowly when reaction was stopped.

3 The amount of cobalt found in aqueous solution.

EXAMPLE 10 The procedure of Example 9 is repeated exceptthat the molarratio of cyanide ion to metal is 1:1. The results obtained from such areaction are similar to those of Example 9.

Similar results are obtained when the reaction is run under a carbonmonoxide pressure of 400 psi. The re- 1 action vessel may be repressuredat regular intervals to maintain the carbon monoxide at about thislevel. Also, petroleum ether can be used for the solvent to extract thenickel carbonyl.

EXAMPLE 1 1 The reaction vessel of Example 3 is filled according to theprocedure of Example 1 with 327 mmoles of ammonium hydroxide, 54,5mmoles of nickel sulfate, 13.6

mmoles of copper sulfate, enough water to make 100 the productsanalyzed. The yield of neckel carbonyl is about 75 percent and about a50 percent yield of copper metal is obtained.

Similar results are also obtained when the catalyst concentration ofcyanide ion is about 0.1 mole percent based on the amount of nickelpresent.

EXAMPLE 12 The process of Example 3 is repeated except that cyanide ioncatalyst at a concentration of about 10 mole percent based on nickel isadded. The rate of nickel carbonyl formation is increased by a factor of10, and high yield of nickel carbonyl is obtained.

Similar results are obtained in this process using nonane as thehydrocarbon solvent. Also, the addition of cyanide ion in-the form ofNaCN brings similar results.

Similar results to those above are obtained when a nickelsulfide-containing ore concentrate is mixed with aqueous ammonia,aerated, and then contacted with carbon monoxide at a pressure of 600psig. and a tempcrture of C. in the presence of cyanide ion catalyst.

EXAMPLE 13 Using the procedure of Example 3, a typical sulfide ore fromMaine is concentrated by known methods to give a nickel-containingsulfide ore concentrate having the following analysis: Ni 8.75%, Fe44.15%, Co 0.85%, Cu 0.73%, S 34.24%, insol. 5.64%, trace metal 3.36%.

This concentrate is mixed with aqueous ammonia, NH OH, and aeratedaccording to known procedures. The aeration of the ammoniacal solutionprecipitates out iron as hydrated ferric oxide. Many other trace metalvalues are insoluble in Nl-1 OH and, after these areremoved, the Ni, Co,and Cu values are left in the ammonia leach solution as the ammoniumsulfate complexes. The ammonium concentration is this solution isadjusted to give a Nl-LOH to nickel ratio of about 4:1 or 6:1 asdesired.

To the solution is now added molar ratio of I I 1 10:1 NiSO :KCN,heptane to form an organic layer on top. The vessel is sealed andpressured with carbon monoxide to 1,600 psig. and the temperature ismaintained at C. for three hours. When the vessel is vented, the organiclayer is drawn off and the ammoniacal solution is removed. Metalliccopper left in the bottom of the reaction vessel is removed from thereaction vessel. I i I I Recovery of metal values is as follows: Cu 53%;Ni 72%, (as Ni(CO) Co 74.7%,(as C080 Another embodiment of thisinvention comprises the discovery that nickel carbonyl catalyzes theformation of copper from ammoniacal solutions of copper ammines. THus,when treated with carbon monoxide, ammoniacal solutions of copper saltswill give copper metal. When the same reaction conditions are em ployedtogether with nickel carbonyl present in the system the yield of coppermetal is increased. This is demonstrated by the following example.

EXAMPLE 14 A glass liner of a rocking autoclave was charged with 9.99 g.of CuSO -5H O, 16 ml. of concentrated ammonium hydroxide, and 35 ml. ofwater. The autoclave was pressured with 600 psig. of carbon monoxide and600 psig. of hydrogen. The resultant mixture was heated for 2 hours at150C. Y

The resultant reaction mixture consisted of a colorless aqueous phase(which turned deep blue on exposure to air) and copper metal. The metalwas filtered off, washed with aqueous ammonia, water and methanol. Afterdrying in vacuo, the product copper weighed 0.56 g. (a 22 percentyield).

In another run, the glass liner was charged with 5.0 g. (20 mmoles) ofCuSO '5H O, 5.25 g. (20 mmoles) NiSO,-6H 16 ml. of concentrated ammoniumhydroxide, 35 ml. of water and 10 ml. of heptane. The autoclave waspressured with 600 psig. each of hydrogen {and carbon monoxide andheated 2.5 hours at 150C. The resultant reaction mixture consisted of anaqueous layer, copper metal, and a colorless organic layer.

The copper metal was removed by filtration, washed and dried in vacuo.The amount of copper was 0.74 grams, a 58 percent yield.

The nickel yield determined by treatment of the heptane layer withbromine in CCl was 52 percent. Similar results are obtained when theheptane is omitted.

A copper sample obtained by the procedure above wherein neckel waspresent in the reaction mixture contained 0.01 to 0.1 percent nickel.

EXAMPLE 15 A glass liner was charged with 5.0 g., 20.0 mmoles CuSO -5HO, 5.25 g., 20.0 mmoles NiSO -6H O, 21 ml. 320 mmoles concentrated NHOH, 25 ml. water, and 10 ml. heptane. The autoclave was pressured with640 psi. hydrogen and 1,200 psi. carbon monoxide, then heated 2.0 hoursat 150C. The reaction mixture consisted of a colorless upper phase,metallic copper, and a light blue aqueous solution. The heptane phasewas siphoned off and combined with subsequent heptane extracts of theaqueous phase. The organic solution was treated with excess bromine incarbon tetrachloride.

The resulting mixture was filtered, washed with carbon tetrachloride,and dried. This gave 2.55 g. of light yellow-brown powder, identified asnickel bromide. The amount isolated corresponded to 1 1.7 mmoles Ni(-CO).,, 58 percent yield based on starting NiSO Copper metal was isolatedas above. The yield was 0.90 g. 14.2 mmoles (71 percent based onstarting CuSO The above example can be repeated by using: copperconcentrations of from 0.001 grams per liter to saturated solution,nickel concentrations of from 0.001 grams per liter to satruatedsolution, ammonia concentrations of from 1 to 10 moles per mole ofmetal, v hydrogen pressures of from zero to 1,200 psig, temperatures offrom 100 to 250C. However, it should be pointed out that the copperconcentration is not critical. In addition, preferred copperconcentrations are from 1 to 100 grams per liter. Preferred nickelconcentrations are from 1 to 150 grams per liter. PrefeiTed ammoniaconcentrations are within the range of from 1 to 10 moles per mole ofmetal. Preferred carbon monoxide pressures are from 200 to 400 psig. Apreferred temperature range is from 100 to 200C. Reaction times are notcritical, times of 1 to 4 hours are usually sufficient. The presence ofan immiscible organic solvent is not essential. However, because thisembodiment lends itself to be an integral feature of a method forseparation of copper metal from nickel carbonyl, it is usually preferredto carry out this embodiment in the presence of a solvent for nickelcarbonyl. Solvents for this purpose and amounts thereof have been setforth above.

The nickel carbonyl need not be formed in situ. Rathre, preformed nickelcarbonyl .can be added to the reaction mixture.

Another embodiment ofthis invention is the catalytig effect of manganesecarbonyl in the production of copper metal from carbon monoxidereduction of ammoniacal copper ammine solutions.

This is illustrated by the following example.

EXAMPLE 16 A glass liner of a rocking autoclave of roughly 300 ml.capacity was charged with Mn (CO) 0.80 g.

Conc. NH.,OH 16 ml.

Water 35 ml.

n-Heptane 10 ml.

The autoclave was pressured with 600 psi of hydrogen and 600 psi ofcarbon monoxide, then heated 2.5 hours at 150. The reaction mixtureconsisted of a colorless aqueous phase, metallic copper, solid Mn (C )w.and a yellow organic phase. The heptane layer was siphoned off, and theremaining catalyst was extracted with heptane and ether. Work up of theorganic extracts gave 0.59 g. Mn (CO) (74 percent recovery). Metalliccopper was filtered off, washed with aqueous ammonia, water, andmethanol. After drying in vacuo, 1.03 g. of copper (16.2 mmoles, 40.5percent yield) was obtained.

The preceding experiment was repeated using the same reaction conditionsand the same quantity of reagents, but leaving out Mn (CO), and heptane.There was obtained 0.56 g. 8.9 mmoles of copper metal, representing 22percent yield. The aqueous phase of the reaction was colorless, butturned to deep blue color when exposed to air.

Because Mn (CO) is a solid, it is preferred that the process beconducted in the presence of an organic solvent. In contrast, Ni(CO) isa liquid and no solvent is required for it to render catalysis of coppermetal preparation.

The above example can be repeated and increased yields of copperobtained by using:

copper concentrations of from 0.001 grams per liter to saturatedsolution,

manganese carbonyl copper ratios of from 0.001 to ammonia concentrationsof from 1 to 10 moles per mole of metal,

hydrogen pressures of from to 1,200 psig.,

carbon monoxide pressures of from 200 to 1,200

psig., I

temperatures of from 100 to 250C.

However, it should be pointed out that the copper concentration is notcritical. In addition, preferred copper concentrations are from 1 to 30grams per liter. Preferredmanganese carbonyl to copper ratio is from0.01 to 0.4. Preferred ammonia concentrations are within the range offrom 2 to 4. Preferred carbon monoxide pressures are from 200 to 400psig. A preferred temperature range is from to 200C. Reaction times arenot critical; times of 1 to 4 hours are usually suffcient.

Another embodiment is the catalytic effect of cobalt carbonyl in theproduction of copper metal from carbon monoxide reduction of ammoniacalcopper ammine solutions. For example, similar results to those obtainedby manganese carbonyl catalysis in Example 16 are obtained when cobaltcarbonyl is substituted for the manganese carbonyl.

The following experiments are an indication that manganese carbonyl alsocatalyzes the formation of nickel carbonyl.

EXAMPLE 17 The glass liner was charged with 10.5 g. 40 mmoles NiSO -6HO, 0.80 g., 2.05 mmoles Mn (CO) 21 ml. conc. NI-I OI-I (c.a. 320mmoles), 25 ml. water, and 10 ml. heptane. The autoclave was pressuredwith 820 psi H and 1,300 psi CO, then heated 2.5 hours at 150, cooled,and vented through a dry ice trap. The reaction mixture consisted of ablue aqueous phase and a yellow organic phase. The heptane layer wassiphoned off and the aqueous phase was extracted with about 30 ml. ofheptane-hexane solution. The combined organic solution was distilled invacuo into a dry icecooled receiver. Work-up of the distillation residuegave 0.53 g., 1.36 mmole Mn (CO) representing 67 percent recovery. Thedistillate, containing Ni(CO) was treated at 76C. with bromine-carbontetrachloride solution until no more gas was evolved and the mixturecontained excess of bromine. The suspension was filtered and washed withcarbon tetrachloride. After drying in vacuo, 5.93 g. of nickel dibromidewas obtained. Thus, the yield of nickel carbonyl was 27.1 mmoles, or 68percent.

The amounts of starting materials used were the same as in the precedingexperiment, except that no Mn (CO) was added in this case. The autocalvewas pressured with 800 psi H and 1,200 psi CO and heated 2.5 hours at150C. Following the same work-up procedure, 4.86 g. of NiBr wasobtained. This corresponded to 22.2 mmoles of Ni(CO),,, 56 percentyield.

As with all processes of this invention described and illustrated by theabove description and examples the processes of the aforesaid examplesare not criti cally dependent on use of n-heptane. When an essentiallywater-immiscible solvent is used, it may be any solvent for nickelcarbonyl. For economic reasons, aliphatic hydrocarbon materials arepreferred solvents. To facilitate Ni(CO) stripping the solventpreferably has a boiling point of at least about 36C. There is nocritical upper limit in boiling point of solvent.

From the foregoing description, it can be readily seen that the processof this invention is highly flexible. Thus, any method for obtainingnickel and its associated metals in the desired form for carbonylationmay be used. A feature of this invention is,therefore, the combinationof various pyrometallurgical, hydrometallurgical, vapometallurgical, andphysical separation processes with carbonylation to obtain and separatenickel and its associated metals. Indeed, such combination results inimproved processes for winning nickel by advantageously using provenfront-end processes in handling various types of ores most economically,dissolving or partially dissolving the nickel values in an aqueousammonium salt or ammonium hydroxide solution and contacting the solutionwith a carbon monoxide-containing gas under conditions whereby thenickel values are reduced to form nickel carbonyl, copper values areprecipitated as metallic copper, and cobalt values remain in aqueoussolution as a cobalt carbonyl anion from which it is readily recoveredby oxidation to hydrated cobalt oxide. Thus, the overall process effectsremoval of nickel and those associated metals from the material providedby the front-end process.

The wide applicability of such improved processes is illustrated bycombining the above-described reductive carbonylation process with asulfide or oxide ore leaching process, a ferronickel process, a blastfurnace or converter matte process using either sulfide or oxide ores oreven a scrap metal recovery process. As a result of such improvedprocesses, substantial savings in operational steps, processing costs,and capital investment are realized. 7

One currently employed process as schematically diagrarnmed in FIG. 2Ashows a process employing crushing and grinding, drying the ore toprepare a material of suitable size, partially reducing the ore to themetals, cooling the reduced ore under non-oxidizing conditions,oxidatively leaching the reduced ore with aqueous ammonia and carbondioxide to dissolve nickel and cobalt as their carbonates. The leachsolution is then boiled to concentrate the solution, recover ammoniavalues, and precipitate basic nickel carbonate. The basic nickelcarbonate is then sintered to produce a nickel oxide product.

FIG. 2B shows the improved-process combining carbonylation after theoxidative leach. Such an improved process allows recovery of nickelmetal and, in addition, cobalt by a simpler process requiring feweroperations and less processing equipment. According to FIG. 2B, thesteps of ore preparation (which include crushing, grinding and drying),reducing and cooling under non-oxidizing conditions are the same as theprocess of FIG. 2A. However, the oxidative leach may be carried outunder more strenuous conditions and significant amounts of cobalt,suppressed in the previous process, are now leached from the ore. Theprevious process having no easy method for separating cobalt findsleaching of the cobalt a liabilityto the process. However, the processof this invention easily separates cobalt and, thus, it becomes an assetto the process. After leaching, the leach solution is subjected tocarbonylation under conditions whereby nickel and cobalt tetracarbonylcompounds are produced. The nickel carbonyl is separated from thesolution and the metal recovered from the carbonyl compounds. The cobaltis separated in a different manner. Thus, a preferred embodiment of thisinvention is a process for recovering nickel values from lateriticnickel ores predominantly of the silicate type ore containing them, saidprocess comprising:

a. subjecting said ore to a reducing roast to convert asubstantialamount of said nickel to nickel metal;

b. cooling the reduced ore under non-oxidizing conditions;

c. oxidatively leaching said reduced ore with an aqueous ammoniacalammonium carbonate solution by injecting an oxygen-containing gas into aslurry of said reduced ore in said ammoniacal ammonium carbonatesolution;

d. contacting the resultant leach solution containing nickel ammoniumsalt complexes with a carbon monoxide-containing gas under conditionswhereby the nickel values are reduced to nickel carbonyl;

e. separating said nickel carbonyl from said leach solution; and

f. decomposing said nickel carbonyl to metallic nickel.

The lateritic nickel ore is prepared for reduction by crushing anddrying. A first crushing, for example, in toothed roll crushers, breadsup larger lumps of ore for convenient drying in a concurrently oil-firedrotary drying kiln. Temperatures in the kiln range from about 1,900F. atthe entrance to about 250F. at the exit. The dry ore averages about 1.4wt.% nickel and 0.1

wt.% cobalt. The dried ore is then finely ground in hammer and ballmills and charged to the reduction furnace.

Reduction is carried out in a multiple hearth furnace using a producergas and additional heat from combustion of fuel oil. A sufficiently lowheating rate permits substantially complete reduction of nickel oxide tometal at less than 1,400F. Reduction is carried out at this temperatureto obtain the maximum amount of nickel as the metal and yet limit theamount of iron and other impurities such as magnesia in the product. Thereduced ore is cooled under non-oxidizing conditions by discharging thefurnace into cooling tubes rotating in a water bath. The temperature ofthe ore on exiting from the coolers is about 300F. The ore is thenplaced in quench tanks containing an ammoniacal ammonium carbonate leachsolution. The leach solution is made by injecting ammonia and carbondioxide into water. High temperatures in the quench tank are preventedby precooling the ammoniacal leach liquor in water-cooled heatexchangers. Such low temperatures minimize ammonia vaporization anddeposition of scale.

From the quench tank, the ore is leached in aerating tanks by injectingan oxygen-containing gas, for example air, into the solution. Theoxidation of nickel dissolves the nickel into the ammonia ammoniumcarbonate solution as a stable hexammine nickel carbonate complex. Also,the recovery process of this invention permits a deep leach which alsodissolves the cobalt values in the ore. Iron deposits out as hydratedferric oxide and can be removed as such from the leach tank.

The dilute leach solution discharges into a series of thickeners whichserve to settle and remove the gangue. The supematent washed leachliquor can then be passed into an autoclave for carbonylation. Theessentially iron-free solution containing nickel and cobalt values iscontacted with a carbon monoxide-containing gas. This operation iscarried out as described above to produce nickel carbonyl and cobalttetracarbonyl anion. Separating of nickel carbonyl from the leachsolution can be carried out by extracting the nickel carbonyl into anessentially water-immiscible, substantially inert solvent for nickelcarbonyl, thus concentrating the nickel carbonyl produced in thesolvent, or when the reaction is essentially complete, additionalamounts of carbon monoxide-containing gas may be passed through thecarbonylated leach solution to vaporize the nickel carbonyl. The nickelcarbonyl is then passed into a decomposition zone to obtain metallicnickel. Decomposition is readily accomplished thermally by knownmethods.

This embodiment of the invention can be illustrated in the followingexamples. Unless otherwise stated, all parts are by weight.

EXAMPLE 1 8 A solution of basic nickel and cobalt carbonates such asresult from the oxidative leach step of the above process, was preparedby dissolving 51 parts of NiCl -6H O and 10 parts of CoCl -6l-I O in 100parts of water. To this solution was added sufficient aqueous sodiumhydroxide to precipitate the metals as Ni(Ol-l and Co- (OH) Afterfiltration, washing, and resuspension in water, 90-400 parts of ammoniumcarbonate and 27 parts of concentrated ammonium' hydroxide were added.The solution was stirred and warmed slightly to yield a blue solution ofnickel and cobalt salts.

The blue solution was then vaporized under vacuum at 35-40C. to decreasethe volume of solution. Any precipitated solids were re-dissolved usingenough aqueous ammonia so that the final solution analyzed as follows:

2 parts Ni 0.2 parts Co parts H 0 2 parts .Nl-l (as concentratedammonium hydroxide) This solution, corresponding to an oxidative leachsolution according to the above process, was placed in a reaction vesselequipped with a stirrer, a thermocouple, a pressure gauge, a gas inlettube, and a vent gas discharge tube. To the solution was added 7 partsof heptane. The autoclave was sealed and pressured to 300 psi. withcarbon monoxide. The stirrer was started and the temperature in thereaction vessel brought up to C. The reaction was continued for 40minutes with carbon monoxide pressure decreasing to 220 psi. indicatingthe carbon monoxide was absorbed in the reaction vessel contents. Thestirrer was stopped and the reaction vessel cooled. The remaining carbonmonoxide was vented and the reaction vessel was opened.

The contents of the reaction vessel has separated into two layers. Theheptane layer was drawn off and the remaining aqueous layer was observedto have the blue color characteristic of nickel and cobalt saltsolutions. Therefore, the reaction, was of low yield. The organic layerwas, therefore, not analyzed for nickel carbonyl. Several runs werecarried out using the procedure of Example 18 except for the addition ofcatalyst and the reaction time. The results are shown in Table ll below.

It will be appreciated by skilled practitioners that the invention doesnot require a solvent for separation of nickel carbonyl. However, it isa preferred embodiment of the invention that the contacting with thecarbon monoxide-containing gas is carried out in the presence of anessentially water-immiscible, substantially inert solvent for nickelcarbonyl whereby said nickel carbonyl formed is concentrated in saidsolvent. As stated previously, the solvent can be any solvent meetingthe above criteria. A preferred solvent is an aliphatic hydrocarbon.

Example 19 in Table II above shows that a catalyst is not necessary forconverting nickel to nickel carbonyl with carbon monoxide. However, itis clear from Examples 20 and 21 that the presence of a catalyst isextremely beneficial. Therefore, it is a preferred embodiment of theinvention that the contacting with the carbon monoxide-containing gas iscarried out in the presence of a catalyst for the formation of nickelcarbonyl. A preferred catalyst is cyanide ion. A most preferred catalystconcentration is from about 0.01 to about I mole of cyanide ion per moleof nickel present.

While the nickel carbonyl may be separated from the aqueous reactionphase, by carrying out the reaction in the presence of a solvent, thenickel carbonyl may also be separated from the leach solution by passingadditional carbon monoxide-containing gas through the

2. A process of claim 1 wherein said solution or slurry is an ammoniumsalt solution or slurry.
 3. A process of claim 2 wherein said ammoniumsalt solution or slurry is an ammoniacal ammonium salt solution orslurry.
 4. A process of claim 3 wherein said ammoniacal ammonium saltsolution is selected from the group consisting of ammoniacal ammoniumchloride, carbonate, sulfate, and mixtures thereof.
 5. A process ofclaim 4 wherein said ammoniacal ammonium salt solution or slurry is anammoniacal ammonium carbonate solution or slurry.
 6. A process of claim5 wherein the molar ratio of ammonia to metal in said ammoniacalammonium carbonate solution is from 0:1 to about 100:1.
 7. A process ofclaim 6 wherein the molar ratio of ammonia to metal in said ammoniacalammonium carbonate solution is from 0:1 to 10:1.
 8. A process of claim 6wherein said reaction is carried out at a pressure of from 50 to about3,000 psig. and a temperature of from about 50* to about 250C.
 9. Aprocess of claim 8 wherein said temperature is from 100* to about 175C.10. A process of claim 1 wherein said reaction is carried out in thepresence of a catalytic amount of a ligand selected from the groupconsisting of cyanide, sulfide, cysteine, and tartrate.
 11. A process ofclaim 10 wherein said reaction is carried out at a temperature of from50* to about 250C. and a pressure of from 50 to about 1,800 psig.
 12. Aprocess of claim 10 wherein said ligand is present at a ratio of from0.01 to 1 mole of said ligand per mole of said nickel.
 13. A process ofclaim 12 wherein said ligand is present at a ratio of from 0.01 to 0.5mole of said ligand per mole of said nickel.
 14. A process of claim 12wherein said ligand is cyanide ion.
 15. A process of claim 1 whereinsaid carbon monoxide-containing gas is selected from the groupconsisting of carbon monoxide and synthesis gas.
 16. A process of claim15 wherein said carbon monoxide-containing gas is carbon monoxide.
 17. Aprocess of claim 1 wherein said contacting is carried out in thepresence of an essentially water-immiscible, substantially inert solventfor nickel carbonyl whereby said nickel carbonyl is concentrated in saidsolvent.
 18. A process of claim 17 wherein said solvent is a saturatedaliphatic hydrocarbon.
 19. A process of claim 4 further characterizeD bycarrying out said contacting in the presence of an amount of cyanide ionsufficient to catalyze the formation of said nickel carbonyl.
 20. Aprocess of claim 19 wherein said contacting is carried out in thepresence of an essentially water-immiscible, substantially inert solventfor nickel carbonyl wherein said nickel carbonyl formed is concentratedis said solvent.
 21. A process of claim 1 wherein said nickel carbonylis separated from said solution by passing a carbon monoxide-containinggas through said solution, allowing said nickel carbonyl to vaporizeinto said carbon monoxide-containing gas and subsequently passing saidcarbon monoxide-containing gas into a thermal decomposition zone whereinsaid nickel carbonyl in said carbon monoxide-containing gas isdecomposed to metallic nickel.
 22. A process of claim 1 wherein saidsolution or slurry is aqueous ammonium hydroxide.
 23. A process for themanufacture of nickel said process comprising a. establishing an aqueoussolution or slurry containing nickel derived from a source of nickelore, b. contacting said solution or slurry with a carbonmonoxide-containing gas under conditions of temperature and pressuresufficient to form nickel carbonyl, c. separating said nickel carbonylfrom said solution or slurry, and d. decomposing said nickel carbonyl toobtain metallic nickel.
 24. A process of claim 1 wherein said aqueoussolution or slurry contains an ammonium salt or ammonium hydroxide and acatayltic amount of cyanide ion and the reaction is carried out at atemperature of from about 50* to about 250 C and a pressure of fromabout 50 to about 3,000 psig.